Purine compound and catecholamine compound containing compositions and methods for administration

ABSTRACT

A purine compound, which has a desired and an undesired effect when a dosage sufficient to induce the desired effect is administered to a mammal, is combined with a counteracting agent, wherein the counteracting agent can reduce the undesired effect when the combination containing an effective amount of the purine compound is administered to a mammal. In a preferred embodiment, an adenosine compound is combined in vitro with a catecholamine in a predetermined ratio to form an adenosine composition. Very high dosages of a purine compound, such as adenosine, ATP or their analogs can be administered to a mammal via administration of compositions containing the purine compound and a counteracting agent, while reducing the dangerous, undesired effects associated with administering the same dosage of purine compound without first combining it with the counteracting agent. New catecholamine compositions are also taught. The purine and catecholamine compositions of the present invention pioneer new therapies which take advantage of the diversity of physiological effects of purine and catecholamine compounds.

RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 08/341,668, filedNov. 17, 1994, now U.S. Pat. No. 5,679,650; which is acontinuation-in-part of U.S. Ser. No. 08/158,012, filed Nov. 24, 1993,now abandoned; which is a continuation of U.S. Ser. No. 08/083,214,filed Jun. 25, 1993, now abandoned; which is a continuation of U.S. Ser.No. 07/756,480, filed Sep. 9, 1991, now abandoned; which is acontinuation-in-part of U.S. Ser. No. 07/521,529, filed May 10, 1990,now abandoned.

This application is related to 08/437,080, filed May 5, 1995, now U.S.Pat. No. 5,677,290; which is a continuation of U.S. Ser. No. 08/203,670,filed Feb. 28, 1994, now abandoned; which is a continuation of U.S. Ser.No. 08/083,214, filed Jun. 25, 1993, now abandoned; which is acontinuation of U.S. Ser. No. 07/756,480, filed Sep. 9, 1991, nowabandoned; which is a continuation-in-part of U.S. Ser. No. 07/521,529,filed May 10, 1990, now abandoned.

FIELD OF THE INVENTION

The present invention is directed to medicinal compositions and methodsfor their administration, and more particularly is directed to purinecontaining compositions, methods for producing purine containingcompositions, and methods for administration of same. In another aspect,the present invention is directed to catecholamine containingcompositions, methods for producing catecholamine containingcompositions, and methods for administration of same.

BACKGROUND OF THE INVENTION

Purine compounds are found in mammalian organisms both intracellularlyand extracellularly, and play vital roles in metabolic processes. Anonlimiting example of the ubiquitous nature of purine compounds inmammalian systems is the purine containing nucleoside adenosine, whichwas reported over 60 years ago to relax coronary vascular smooth muscleand to impair atrioventricular conduction; adenosine has also been foundto have antinociceptive properties and has recently been proven to beuseful as an anesthetic. The widespread actions of adenosine includeeffects on the cardiovascular, nervous, respiratory, gastrointestinal,renal and reproductive systems, as well as on blood cells, adipocytes,and immune systems. Very small doses of adenosine (0.01-0.25 mg/kg),provided as a single bolus injection, have been suggested for thetreatment of supraventricular tachycardia. A continuous intravenousinfusion of up to 0.2 mg/kg/min adenosine for a duration of about 6minutes has been also suggested for use in diagnostic myocardialimaging. Likewise, the phosphorylated adenosine nucleoside, or adenosinenucleotide, has also been found useful in inducing an anesthetic effect(a phosphorylated nucleoside is a nucleotide). Use of adenosinecompounds in anesthesia is discussed in more detail in U.S. Pat. No.5,677,290, entitled THERAPEUTIC USE OF ADENOSINE COMPOUNDS. The methoddescribed in U.S. Pat. No. 5,677,290 involves a great improvement inanesthesia by administering up to 5 mg/kg/min adenosine or ATP to amammal via a continuous infusion; the dosage is adjusted in response tocardiovascular changes which are due to surgical stimulation. At thedosages used, the anesthetic effect is slowly induced, and the patientmust be carefully monitored. It is believed that the slow induction ofan anesthetic effect is due to the low dosage of adenosine provided, butit was not believed safe to increase the dosages to more quickly achievean anesthetic effect.

It is believed that the activity of purine compounds is mediated by cellsurface receptors specific for a particular purine compound. Dependingon a compound and its receptor, binding of the compound to the receptorcan be reversible, and have a variety of effects. Further, it isbelieved that certain compounds can bind to more than one receptor in acompetitive fashion with other compounds. In a process, sometimesreferred to as biofeedback, the binding of a first compound to aparticular receptor or the presence of a first compound may induce thebody to produce another agent which counteracts one or more of theeffects of the first compound. For example, endogenous substances knownas catecholamines, such as those produced by the nerve endings and theadrenal glands, may be released in response to a stressful situation(e.g., norepinephrine, epinephrine, and dopamine). For example, theendogenous production/release of tiny amounts of catecholamines causesincreased heart rate and vasoconstriction, which the body responds to bythe production of tiny amounts of adenosine and ATP which are believedto counteract certain of the effects of the increased endogenouscatecholamines by different receptor mechanisms.

Considerable research has been directed to purine compounds since Druryand Szent-Gyorgyi reported in 1929 on the physiological actions ofadenosine on cardiovascular function. Several classes of purinereceptors have been identified, and adenosine and adenosinetriphosphate, ATP, have been demonstrated as endogenous protectivesubstances. Although certain purine compounds have significantbeneficial physiological capabilities, the aforementioned ubiquitousnature and effects of purine compounds also tends to make it difficultto use them therapeutically. In other words, administration of purinecompounds to a mammal will have both desired and undesired effectsdepending on patient physiology and the dosages provided.

Furthermore, because these purine compounds such as adenosine areconsidered toxic at concentrations that have to be administered to apatient to maintain efficacious extracellular therapeutic level, theadministration of adenosine alone has been considered of no use orlimited therapeutic use. Therefore, pharmacologists have directed theirefforts to achieving high local extracellular level of adenosine by a)inhibiting the uptake of adenosine with reagents that specifically blockadenosine transport; b) prevention of the metabolic degradation ofadenosine; c) the use of adenosine analogs which will bind to specificadenosine receptors; and recently d) the use of adenosine via itsprecursor, AICA riboside, which has been the subject of a number ofpublications and patents (U.S. Pat. Nos. 5,082,829; 5,132,291;5,187,162; 5,200,525; 5,236,908). However, the above approaches stillhave major disadvantages associated with their use. The metabolic anduptake blocker strategy is very much restricted in character due to thelimited ability of tissue to generate purine compounds, and theadenosine agonist approach has the substantial peripheral side effectsassociated with these agents, such as hypotension, bradycardia, etc.Thus, despite all the intense efforts in basic sciences andpharmaceutical research, to this date, there has been little success indeveloping agents that can be used as therapeutic drugs to fullyactivate purine receptors without side effects. Therefore, until now,there has been no successful medical treatment for prevention ortreatment of ischemic damage.

For more information on purine compounds and purine receptor agonists,see Ely et al., "Protective Effects of Adenosine in MyocardialIschemia", Circulation, 85: 893-904 (1992); Miller et al., "TherapeuticPotential for Adenosine Receptor Activation in Ischemic Brain Injury,"J. Neurotrauma, 9: 563-77 (1992); Williams, "Adenosine Receptors as DrugTargets: Fulfilling the Promise?," in Jacobson et al., Ed., Purine inCellular Signaling: Targets for New Drugs, New York, Springer-Verlag(1990)(See particularly page 175); Lawson et al., "Preconditioning:State of the Art Myocardial Protection," Cardiovascular Research, 27:542-50 (1993); Rudolphi, "Manipulation of Purinergic Tone as Mechanismfor Controlling Ischemic Brain Damage," in Phillis, J. W., Ed.,Adenosine and Adenine Nucleotides as Regulators of Cellular Function,Boca Raton, CRC Press (1991); Berne, R., "Adenosine--a Cardioprotectiveand Therapeutic Agent," Cardiovascular Research, 27:2 (1993); Phillis etal., "Roles of Adenosine and Adenine Nucleotides in the Central NervousSystem," in Daly et al., Eds., Physiology and Pharmacology of AdenosineDerivatives, Raven Press, New York (1983); Galinanes, "Should AdenosineContinue To Be Ignored As A Cardioprotective Agent In CardiacOperations?," Journal of Thoracic and Cardiovascular Surgery, 105:180-183 (1993); Jacobson et al., "Novel Therapeutics Acting Via PurineReceptors," Biochemical Pharmacology 41: 1399-1410 (1991); U.K. Patent797,237; U.S. Pat. No. 4,514,405; U.S. Pat. No. 4,590,180; U.S. Pat. No.4,605,644; U.S. Pat. No. 4,673,563; U.S. Pat. No. 4,880,783; U.S. Pat.No. 4,880,918; U.S. Pat. No. 5,049,372; U.S. Pat. No. 5,070,877; U.S.Pat. No. 5,104,859; Daval et al., "Physiological and PharmacologicalProperties of Adenosine Therapeutic Implications," Life Sciences 49:1435-1453 (1991); Dubyak et al., Eds., Biological Actions ofExtracellular ATP, Annals of the New York Academy of Sciences v. 603,New York, N.Y. Academy of Sciences (1990); Imai et al., Eds., Role ofAdenosine and Adenine Nucleotides in the Biological System. Metabolism,Release, Transport. Receptors, Transduction Mechanisms and BiologicalActions, Amsterdam, Elsevier (1991); Ribeiro, Ed., Adenosine Receptorsin the Nervous System, London, Taylor & Francis (1989); Williams, Ed.,Adenosine and Adenosine Receptors, Clifton, N.J. The Humana Press(1990); Tsuchida et al., "Pretreatment with the adenosine A₁ selectiveagonist, 2-chloro-N6-cyclopentyladenosine (CCPA), causes a sustainedlimitation of infarct size in rabbits," Cardiovascular Research,27:652-66 (1993); Fukunaga et al., "Hypotensive effects of adenosine andadenosine triphosphate compared with sodium nitroprusside," Anesthesiaand Analgesia 61:273-278 (1982); Fukunaga et al., "Effects ofintravenously administered adenosine and ATP on halothane MAC and itsreversal by aminophylline in rabbits," Anesthesiology, 71:A260 (1989);Drury et al. "The physiological activity of adenine compounds withspecial reference to their action upon the mammalian heart", Journal ofPhysiology (London) 68:213-37 (1929); Olsson et al. "Cardiovascularpurinoceptors," Physiological Reviews, 70:761-809 (1990); Downey et al.,Ed. "Spotlight on the cardioprotective properties of adenosine",Cardiovascular Research, v. 27, No. 1 whole issue (1993); Rudolphi etal., Neuroprotective role of adenosine in cerebral ischemia," Trends inPharmacological Sciences, 13:439-45 (1992); and Williams, "Purinergicpharmaceuticals for the 1990s," Nucleosides & Nucleotides, 10:1087-99(1991); U.S. Pat. Nos. 5,082,829; 5,132,291; 5,187,162; 5,200,525;5,236,908; Homeister et al., "Combined adenosine and lidocaineadministration limits myocardial reperfusion injury," Circulation82:595-608 (1990); Mullane K, "Acadesine: the prototype adenosineregulating agent for reducing myocardial ischaemic injury,"Cardiovascular research 27:43-7 (1993); Van Belle H, "nucleosidetransport inhibition: a therapeutic approach to cardioprotection viaadenosine?," Cardiovascular Research 27:68-76 (1993); all of which areincorporated by reference. Perhaps the greatest problem with attempts toutilize purine compounds as therapeutic agents is due to the undesiredand often fatal side effects associated with providing sufficientamounts of a purine compound to a patient to induce a desired effect.For example, it has been well documented that adenosine plays a key rolein the endogenous defenses of the brain against the damaging effects ofischemia. Moreover, adenosine has been reported to protect the heartwhen given both prior to ischemia and at reperfusion; however,intravenous administration of adenosine or even an A₁ selective agonisthas been shown to cause profound hypotension (A₁ represents one of thepurported adenosine receptors in mammalian systems). In another example,anesthesia is induced in a mammal by administering large amounts ofadenosine or ATP; however, anesthetically effective dosages can be fatalto the recipient if extreme care is not followed in administering same(e.g., titration of adenosine in response to accurate monitoring ofpatient vital signs) or if a counteracting agent is not providedpromptly in response to dangerous patient vital function levels. Evenwith prior or subsequent provision of agents to counteract certainundesired effects of administering the large dosages of adenosine, or anadenosine analog, sufficient to induce anesthesia, dangerous variationsin vital functions can result. This "pendulum effect" on patientphysiological processes, which is reflected in large changes in patientvital signs, such as but not limited to blood pressure, heart rate, andrespiration, discourages the therapeutic use of purine compounds.

Therefore, there is a need for purine compositions comprising a purinecompound which can be more easily and safely administered in asufficient amount to induce a desired effect without inducing anundesired effect which is usually associated with administering the sameamount of purine compound alone. Most prior attempts to counteract theundesired effects of administering a purine compound have involved theuse of receptor specific antagonists. Furthermore, it was believed that,due to the dissimilar structure and function of the purine compoundswith respect to the agents which counteract certain undesired effects ofadministering the purine compounds, that the purine compounds andcounteracting agents could not be simultaneously used or mixed togetherin-vitro and still be safely administered for therapeutic purposes.

SUMMARY OF THE INVENTION

Briefly, and in general terms, the present invention provides for purinecompositions and methods of administering the purine compositions, inwhich a synergistic and unexpected beneficial result is obtained bycombining a purine compound with a counteractive agent, wherein thependulum effect or radical variation in certain patient vital functionshave been greatly reduced, and high dosages of a purine compound,previously believed to cause a dangerous or fatal undesired effect, canbe safely administered to induce a desired effect while reducing anundesired effect.

Thus, the present invention is directed to purine compositions, andmethods of administering the purine compositions. The purine compositionpreferably comprise a purine compound and a counteractive agent, inwhich the purine compound induces a desired effect and an undesiredeffect when administered in an effective amount to a mammal withoutadministering the counteractive agent, and the counteractive agent, whencombined with the purine compound prior to administration of theeffective amount of the purine compound, reduces an undesired effect ofthe effective amount of the purine compound upon administration of thecombination to a mammal.

In a preferred embodiment, purine compounds capable of inducing adesired effect, such as but not limited to central nervous systeminhibition, neuroprotection, autonomic nervous system modulation orinhibition, cardiac protection, and respiratory protection,analgesia/anesthesia but which also induce an undesired effect, such asbut not limited to severe hypotension and cardiodepression, are combinedin vitro with a counteractive agent which reduces an undesired effectwhile permitting the purine compound to induce a desired effect when themixture is administered. Compositions in accordance with the presentinvention can be formulated batchwise long periods of time in advance ofadministration, or, for example, can be mixed in a suitable fittingattached to an IV set just prior to passage into a patient, or thecomponents of the composition can be simultaneously administered. In apreferred embodiment, the purine compound is selected from the groupconsisting of adenosine, adenosine analogs, phosphorylated adenosine,and phosphorylated adenosine analogs, and is combined with acounteractive agent. In a preferred embodiment, the counteractive agentis a catecholamine, such as but not limited to epinephrine,norepinephrine, dopamine, dobutamine, and phenylephrine.

In another aspect, a purine composition is formed by combining a purinecompound, a counteractive agent, and a purine compound potentiatorand/or a CNS depressant. The potentiator may be a compound whichinhibits uptake of the purine compound, or a compound which interfereswith the ability of endogenous enzymes to metabolize or otherwisedegrade the purine compound, or a compound which enhances adenosinerelease or a combination of any of them. The potentiator may becompounds such as but not limited to an adenosine uptake (transport)inhibitor (e.g., dipyridamole); an adenosine deaminase inhibitor (e.g.,deoxycoformycin, and erythro-9-(2-hydroxy-3- nonyl)adenine); a precursor(e.g. AICA riboside); a CNS depressant (e.g., a benzodiazepine, such asdiazepam, midazolam, and flumazenil, an opioid, such as morphine,fentanyl, and sufentanil, or a barbiturate, such as thiopental, andmethohexital), etomidate, propofol; an adrenergic α₂ - agonist (e.g.,clonidine, and dexmedetomidine); or a non-steroidal anti-inflammatorydrug (e.g. aspirin, ibuprofen, ketorolac).

In another aspect, the present invention has led to the discovery thatthe multiple effects of the present composition can be used in concertwith other drugs producing synergistic effects of their combinedactivity. The present composition can be used as a carrier of otherdrugs such as antibiotics, antipyretics, anti-viral, anti-cancer,anti-toxin, chemotherapeutic agents, potassium channel openers, and thelike. The effects of the present composition as a blood flowregulator/modulator will selectively target pathological tissues/organsand will enhance the desirable effects of other drugs as well. Forexample, the affirmative and desirable effects of opioids,benzodiazepines and the like, can be enhanced while the side effectsand/or undesirable effects of such drugs can be counteracted. Thus thecombined use of various drugs as in the present composition can act ascatalysts. For example, by the methods and compositions according to theinvention, the respiratory depression effects caused by the opioids andthe benzodiazepines can be counteracted, while the salutary effects suchas the analgesic and sedative effects can be potentiated.

In another aspect, the present invention has also led to the discoverythat surprisingly large dosages of a catecholamine compound, previouslythought sufficient to induce dangerous or fatal side effects, can beadministered by combining the catecholamine compound with acounteractive agent prior to administration, wherein the catecholaminecompound can induce a desired effect upon administration in an effectiveamount, while the counteractive agent reduces an undesired effect oreffects upon administration of the combination to a mammal. In apreferred embodiment, the catecholamine is combined with a purinecompound to form a catecholamine composition capable of inducing adesired catecholamine effect while reducing one or more undesiredeffects which would result if the catecholamine had been administeredwithout first being combined with the purine compound.

In another aspect, it has been surprisingly discovered that high dosagesof a purine compound or a catecholamine compound can now be safelyadministered to a mammal by mixing the appropriate ratio of purinecompound or catecholamine compound with a counteracting agent. Forexample, higher dosages of a purine compound and a catecholaminecompound can be safely administered to a mammal than previously thoughtpossible by combining the purine compound and the catecholamine compoundin predetermined ratios prior to administration. Appropriate ratios ofpurine compound or catecholamine compound to counteracting agent inpharmaceutical compositions according to the present invention can bereadily determined by one of ordinary skill in the art by performing afew routine tests, which involve the monitoring of vital signs ofinterest (e.g., blood pressure, heart rate, respiration) whileadministering varying ratios of purine compound or catecholaminecompound to counteracting agent, and at varying compound dosages.

By way of a nonlimiting example, initially administering low dosages(e.g., dosages known to be safe) of a purine compound combined with acounteracting agent in varying ratios will enable determination of theappropriate ratio of purine compound to counteractive agent which beginto induce a desired effect while reducing an undesired effect; dosagescan then be increased and the ratio of purine compound to counteractingagent adjusted to optimize the desired effect achieved while minimizingan undesired effect. In a preferred embodiment, a purine composition,comprising between about 1 part by weight norepinephrine combined withabout 25 to 2,000 parts by weight adenosine can be administered to amammal to induce a desired effect while reducing an undesired effect,wherein the undesired effect would occur to a much greater degree wereit not for the presence of the norepinephrine in the composition. Othernonlimiting examples of preferred inventive compositions includecompositions comprising 1 part epinephrine combined with between about50 and about 4,000 parts by weight adenosine, compositions comprisingone-part by weight phenylephrine combined with about 10 to about 200parts by weight adenosine, and compositions comprising one part byweight dopamine combined with about two to about five parts by weightadenosine. The preceding compositions can have varying dosages ofadenosine.

Catecholamine compositions in accordance with the present invention canbe formed by combining a catecholamine compound with a counteractingagent and determining the appropriate dosages and ratios for obtainingthe desired effect while minimizing undesired effects.

The same principle can be applied for the use of adenosine analogs thathave much longer effects. For this, longer acting catecholamines can becombined in the composition, or a separate, infusion of counteractivecatecholamines can be administered in one or more stages, preferably ina continuous infusion commencing at some time following infusion of aninitial mixture of an adenosine analog and catecholamine. In addition,the composition can be formulated with an additive that can make itabsorbable from gastrointestinal tracts/organs, and be easily ingested(taken orally, enterally).

One of ordinary skill in the art will recognize that the ratios ofcatecholamine compound or purine compound to counteracting agent can beadjusted depending on patient physiology, vital signs, and thetherapeutic purpose (e.g., a hypotensive and/or bradycardic patient willrequire less adenosine to induce normotension, while a hypertensiveand/or tachycardiac patient will require more adenosine to induce thesame effect). Likewise, dosage will depend on the desired effect andpatient physiopathology. The compositions of the present invention maybe formed in combination with pharmaceutically acceptable carriers, andstored in accordance with standard procedures and precautions formedicinal compositions. The present invention pioneers the use of purinecompounds to efficaciously activate purine receptors for therapeuticpurposes.

The present invention pioneers the therapeutic use of high dosages ofpurine compounds and catecholamine compounds for a wide variety of uses,as well as pioneers the use of new and useful purine and catecholaminecompositions formed by combining a purine compound or a catecholaminecompound with a counteracting agent. For example, purine compositionsprepared in accordance with the present invention can be administered inan amount effective to induce anesthesia and analgesia faster and/ormore safely than present anesthetic methods. Further, administration ofpurine compounds according to the present invention has demonstrated CNSinhibitory effects, and the effects of modulation of the autonomicnervous system and modulation of circulation, respiration as well ashomeostatic metabolism. It may be used in cardioprotection,neuroprotection, pulmonary protection, metabolic homeostasispreservation, sedation, anethesia, antipyretic, antihypertensivetreatment, and prevention and/or treatment of ischemia/hypoxia.

The invention is further described and illustrated by the followingdetailed description and nonlimiting examples.

DESCRIPTION OF THE DRAWINGS

FIGS. 1(a)-(d) are blood pressure (in mmHg) recordings over timefollowing administration of bolus injections of a catecholamine alone,adenosine alone, or varying combinations of adenosine with acatecholamine;

FIGS. 2(a)-(b) are blood pressure (mmHg) tracings from a rabbitadministered bolus injections of adenosine alone, norepinephrine alone,or a combination of adenosine and norepinephrine;

FIG. 3 illustrates sedative and antinociceptive thresholds in responseto electrical tail stimulation, ETS, before and after administration ofa mixture of adenosine, catecholamine, and benzodiazepine;

FIG. 4(a) is a blood pressure tracing over time which illustrates theeffects of administering bolus injections of ATP and norepinephrine;

FIG. 4(b) is a blood pressure tracing over time which illustrates thereduction in the blood pressure pendulum effect when high dosages of ATPcombined with norepinephrine are administered from a pre-mixed solution;

FIG. 5 illustrates the duration of the sedative and analgesic effectsafter administration of diazepam (2 mg/kg) and AC (ATP: 200 mg/kgcombined with NE:0.8 mg/kg);

FIGS. 6(a)-(j) illustrate the cardio-respiratory and metabolicassessment following high dose-fentanyl administration in two groupspretreated with: a) saline, or b) AC (ATP:100 mg/kg and NE:0.2 mg/kg);

FIGS. 7(a)-(d) illustrate the rates of mortality and pulmonary edemaover time due to infusion of norepinephrine as a cardiotoxic stimulantwith and without adenosine/catecholamine compositions of the invention,showing the cardiopulmonary protective effects ofadenosine/catecholamine compositions of the invention;

FIGS. 8(a)-(b) illustrate the rates of mortality and pulmonary edemaover time due to infusion of epinephrine as a cardiotoxic stimulant withand without adenosine/catecholamine or ATP/catecholamine compositions ofthe invention, showing the cardiopulmonary protective effects ofadenosine/catecholamine compositions of the invention;

FIG. 9 is a chart illustrating effects on metabolic acidosis due tostress and the effects on maintaining metabolic homeostasis andprotection from ischemia by administration of adenosine/catecholaminecompositions of the invention;

FIG. 10 is a blood pressure recording over time following an initialadministration of a longer lasting adenosine analog, R-PIA, along withnorepinephrine, and subsequent administration of norepinephrine,illustrating a method of administering longer lasting adenosine analogswith catecholamine according to the invention;

FIG. 11 is a blood pressure recording over time following an initialadministration of a longer lasting adenosine analog, R-PIA, along withnorepinephrine, and subsequent administration of norepinephrine,illustrating another method of administering longer lasting adenosineanalogs with catecholamine according to the invention; and

FIG. 12 is a blood pressure recording over time following an initialadministration of a longer lasting adenosine analog, NECA, along withnorepinephrine, and subsequent administration of norepinephrine,illustrating another method of administering longer lasting adenosineanalogs with catecholamine according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has been surprisingly discovered that, despite the dissimilarstructure and function of purine compounds and their counteractingagents, that they have sufficiently similar pharmacokinetics to be usedsimultaneously or to be combined together in vitro and administered, sothat certain of the undesired effects of administering purine compoundsalone can be offset by the coadministered counteracting agents. Further,it has been surprisingly discovered that the in-vitro combination of thepurine compounds with counteracting agents does not result in an adversereaction in-vitro, or in-vivo following administration, and thatsurprisingly improved results can be achieved by administering a mixtureof a purine compound with a counteractive agent. In fact, it is amazingthat such unforseen synergistic effects of two potent and antagonisticsubstances when used simultaneously or combined together in vitro couldhave such enhanced and significant biological effects. For the purposesof this disclosure, a purine compound is defined as a compound includingthe purine functionality (by way of nonlimiting example, adenosine), apurine analog, or a purine receptor agonist, which has at least onedesired effect and at least one undesired effect upon administration toa mammal in an amount sufficient to induce a desired effect ("purineeffect"). A catecholamine compound is defined herein as a catecholamine(by way of nonlimiting example, norepinephrine), a catecholamine analog,or a catecholamine receptor agonist having at least one desired effect("catecholamine effect") and at least one undesired effect uponadministration to a mammal of an amount sufficient to induce a desiredeffect. A counteracting agent is defined as an agent which is capable ofreducing an undesired effect caused by administration to a mammal of aneffective amount of a purine compound or a catecholamine compound. Asused hereinafter, the term "AC" refers to a combination or simultaneousadministration of adenosine, adenosine analogs, phosphorylatedadenosine, or phosphorylated adenosine analogs, and catecholamine, and"ACB" is the combinational use of AC and benzodiazepine.

As shown in the figures for purposes of illustration and as discussedabove, the present invention has tremendous benefits to medicine, andpioneers new purinergic therapies and adrenergic therapies. This ispartly because larger doses of purine compounds and catecholaminecompounds than were previously thought possible can now be safelyadministered to a mammal to induce a desired effect while reducing atleast one undesired effect previously associated with administering sucha dosage. As is illustrated by the blood pressure, BP, tracings in FIG.1(a), provision of a purine compound, such as adenosine, or acatecholamine compound, such as norepinephrine, alone, induces severealterations in patient vital functions. It is noted that, although bloodpressure is primarily used in this disclosure to demonstrate thisphenomenon, other patient vital functions can be monitored as well toillustrate the beneficial effects of the present invention. For example,in addition to blood pressure, other patient vital functions which canbe monitored include but are not limited to electrocardiogram, EKG,respiratory rate, RR (breaths per minute), heart rate, HR (beats perminute, BPM), body temperature, and blood gas data: PaCO₂ and PaO₂ forrespiratory parameters, pH, and base excess (BE) for metabolicparameters.

The present invention enables the therapeutic use of purine andcatecholamine compounds by reducing the severe side effects associatedwith administering a sufficient dosage of a purine compound or acatecholamine compound to induce a desired effect. The attenuation ordampening of undesired radical alterations in certain patient vitalfunctions by administration of compositions prepared in accordance withthe present invention is made clear by the following nonlimitingexamples.

As a nonlimiting example of how one of ordinary skill in the art woulddetermine the appropriate ratio of a purine compound combined with acounteracting agent in a composition formed in accordance with thepresent invention, the following steps can be followed: A desired effectof administering a purine compound can be achieved by administering asufficient amount of the purine compound to a mammal to induce thedesired effect. For example, adenosine can be administered to a patientto induce an analgesic/anesthetic effect provided a sufficient amount ofadenosine is administered to the patient. However, administering adosage of adenosine to a mammal sufficient to induceanalgesia/anesthesia will also induce severe hypotension andcardio-depression, which can be monitored by blood pressure recordingdevices and heart rate (EKG) monitors. The degree of hypotension andcardio-depression can be sufficient to cause irreversible damage topatient vital organs, or may even induce death. Therefore, it isnecessary to first determine the appropriate ratio of adenosine tocounteracting agent in the purine compound composition to beadministered to the patient. In order to do this, the patient vitalfunctions of interest, for example, the heart rate and blood pressure,can be monitored prior to and during administration of compositionscontaining varying ratios of the purine compound to the counteractingagent (e.g., adenosine to catecholamine ratio).

Initially, only small dosages of the purine compound which are known notto cause dangerous side effects should be administered in combinationwith a counteracting agent which is also provided at a dosagesufficiently small that it is known to cause no adverse side effects.The ratios of the purine compound to the counteracting agent can then betitrated to attenuate radical fluctuations in the vital function ofinterest. Thereafter, the combined dosages of purine compound andcounteracting agent can be gradually increased, with the ratio of thepurine compound combined with counteracting agent adjusted to optimizepatient vital functions of interest.

Because of the similarity of physiological response to purine compoundsand catecholamine compounds in humans and in rabbits, rabbits provide anideal source of information on the appropriate ratios of purine compoundor catecholamine compound to counteracting agent in compositions to beadministered to a human. Those of ordinary skill in the art willimmediately recognize that dosages and ratios may vary from patient topatient depending upon the type of therapy desired and on the particularpatient. As with the administration of any drug, those of ordinary skillin the art should follow normal procedures for minimizing the risk ofadverse reactions when supplying compositions in accordance with thepresent invention to a patient receiving other drugs or therapies. SeeGilman et al., Eds., Goodman and Gilman's. The Pharmacological Basis ofTherapeutics, 9th ed., New York, Pergamon Press (1990); and Katzung,Ed., Basic and Clinical Pharmacology, 5th Ed., Norwalk, Appleton & Lange(1992).

Compositions of the present invention may be administered withpharmaceutically acceptable carriers, and may be combined with apotentiator, which may increase or prolong the beneficial effects of thepurine or catecholamine compound. In the event of contraindications,dosages may be adjusted by a physician administering compositions of thepresent invention, or additional amounts of a purine compound, acatecholamine compound, and/or a counteracting agent may beadministered.

Some patients have reported discomfort, such as headaches, flushing, andangina-like chest pain following administration of purine compounds,such as adenosine. In order to minimize this discomfort, a centralnervous system, CNS, depressant may be administered to the patientfirst, or may be combined with a purine composition or a catecholaminecomposition prepared in accordance with the present invention. SuitableCNS depressants include but are not limited to benzodiazepines, opioids,barbiturates, and propofol.

In a preferred embodiment, adenosine compounds can be combined with anadenosine potentiator, such as but not limited to an adenosine uptakeinhibitor (e.g., dipyridamole, dilazep, benzodiazepine), and/or anadenosine deaminase inhibitor (e.g., 2'deoxycoformycin, anderythro-9-(2-hydroxy-3-nonyl)adenine). Thus, in an alternativeembodiment, a purine compound or catecholamine compound combined with acounteracting agent is also combined with a purine compound orcatecholamine compound potentiator. In yet another embodiment, a purinecompound or a catecholamine compound combined with a counteracting agentare also combined with a CNS depressant. In another embodiment, a purinecompound is combined with a counteracting agent, a CNS depressant, and apurine compound potentiator. In yet another embodiment, a catecholaminecompound is combined with a counteracting agent, a CNS depressant, and acatecholamine compound potentiator.

The protective effects of administering a purine compound, such asadenosine, combined with a counteracting agent, such as a catecholamine,have also been clearly demonstrated by administration of a purinecomposition prepared in accordance with the present invention to amammal suffering from severe respiratory depression and seizure activitycaused by high dose opioids like fentanyl. Administration of a purinecomposition in accordance with the present invention also protectsmammals from noxious stimulation by inducing both sedative and potentanalgesic effects, while protecting the cardiovascular and metabolicfunctions which are usually affected by stressful conditions, such asexcessively high plasma catecholamine levels and pain.

With reference to FIGS. 10-12, the method of the invention foradministering a purine compound in combination with a catecholaminecounteractive agent can also further comprise the administration of oneor more separate infusions of additional catecholamine counteractiveagent following the initial infusion of purine compound andcatecholamine counteractive agent. Adenosine analogs that can be used inthe compositions and method of the invention include, but are notlimited to, 5'-N-ethylcarboxamidoadenosine (NECA), R(-)N⁶-(2-phenylisopropyl) adenosine (R-PIA), 2-chloroadenoine (2-CADO), N⁶-cyclopentyladenosine (CPA), and N⁶ -cyclohexyladenosine (CHA), forexample. Such adenosine analogs can have longer lasting effects in thebody than adenosine, and in particular can have longer lasting effectsin the body than catecholamines typically co-administered withadenosine, such as norepinephrine, for example, so that theco-administration of catecholamine with an adenosine analog can furtherinclude judicious administration of at least one separate infusion of aselected catecholamine as the effects of a selected adenosine analogcontinue even beyond administration is stopped. The additional infusionof the selected catecholamine counteractive agent following the initialinfusion of the mixture is preferably administered by a separate,continuous infusion of the catecholamine, and in one preferredembodiment, the additional infusion of catecholamine is administered instages of progressively reduced dosages over time, as the selectedadenosine analog is gradually metabolized.

The beneficial effects of administering the purine compositions andcatecholamine compositions of the present invention to mammals arefurther illustrated by the following nonlimiting examples.

EXAMPLE 1 Hemodynamic Effects of Intravenous Administration of aCombination of Adenosine-Catecholamine (AC)

Materials and Methods:

Drugs: Adenosine and ATP (adenosine 5'-triphosphate, disodium salt) wereobtained from Kyowa Hakko Kogyo Co., Tokyo, Japan, and dissolved instandard saline solution. Norepinephrine bitartrate injection(LEVOPHED®) was obtained from Winthrop Pharmaceuticals, and Midazolamhydrochloride was obtained from Roche Laboratories.

Unmedicated, healthy New Zealand white rabbits (male and female),weighing 2.5-2.7 Kg were studied. Rabbits were chosen because they arean excellent indicator of how these drugs and methods will work inhumans. Anesthesia was initially induced with halothane 3-4% in oxygenusing a face mask, and the animals were allowed to breath spontaneously.A tracheostomy was performed on each rabbit, and a 3.5 F (French size)cuffed pediatric endotracheal tube was inserted into the trachea. Theinhaled concentration of halothane was then lowered, and maintained with1.5-2% halothane in 100% oxygen during the preparation. Localinfiltration with lidocaine (1% solution) was done when a tracheostomyand femoral cut down were performed. An ear marginal vein and a centralartery were cannulated with 22 and 24 gauge plastic catheters for drugand fluids administration and for blood sampling. After intravenousaccess was established, lactated Ringer's solution was started at 5ml/kg/hr for fluid maintenance. The femoral artery was cannulated with apolyethylene catheter (PE 120) which was placed with its tip in themid-thoracic aorta to measure central arterial blood pressure. Thecatheter was well secured and the skin was closed. The heart rate wascontinuously monitored via percutaneous leads (II) electrocardiograph(EKG), connected to a Hewlett Packard 78304A polygraph and recorded on aHewlett Packard 78172A recorder. Body temperature was continuouslymonitored by means of a rectal probe, and maintained between 38.5-39.5°C. with the aid of a heating lamp.

After completion of the experimental preparation, halothane wasdiscontinued and the rabbits were placed in a sling in a natural,physiological posture which allowed the animal's head and legs freedomto move. After complete recovery from the halothane anesthesia, thefollowing control measurements were taken from the unanesthetizedanimals: systolic blood pressure (SBP), diastolic blood pressure (DBP),mean arterial pressure (MAP), Respiratory Rate (RR), Heart Rate (HR),ECG, Body Temperature (BT), arterial blood gases: PaCO₂, PaO₂, pH, andbase excess (BE). Blood gases were measured with a Radiometer ABL 30blood gas analyzer.

Results and Conclusions:

In order to determine the optimal concentration ratio of the componentsof the adenosine-catecholamine, AC, composition, various concentrationsof an adenosine compound (A) and a catecholamine (C) alone wereseparately injected, and then mixtures of adenosine with catecholaminehaving varying ratios of adenosine to catecholamine were tested in thein vivo experimental animal model. The results of these experiments areshown in FIGS. 1 and 2 which illustrate the effects on blood pressure(mmHg) over time from administering a purine compound or catecholaminealone, or from administering varying compositions of a purine compoundcombined with a catecholamine.

The above process was repeated several times for each animal, and withvarious combinations of adenosine and a catecholamine respectively, asillustrated in FIGS. 1(a)-(d). FIG. 1(a) has six separate tracings whichresult from administration of purine and catecholamine compounds asfollows: FIG. 1(a), tracing (a)1: 20 μg norepinephrine; (a)2: 5 mgadenosine; (a)3: 10 mg adenosine; (a)4: 20 mg adenosine; (a)5: 40 mgadenosine; and (a)6: 20 mg adenosine. FIG. 1(b) illustrates fourtracings which result from administration of the following compositionsformed from 20 mg adenosine combined with varying amounts of acatecholamine: (b)1: 1 part norepinephrine mixed with 250 partsadenosine (i.e., 20 mg adenosine combined with 0.08 mg norepinephrine);(b)2: 1 part norepinephrine mixed with 500 parts adenosine; (b)3: 1 partnorepinephrine mixed with 1,000 parts adenosine; (b)4: 1 partnorepinephrine mixed with 2,000 parts adenosine. FIG. 1(c) illustratesfour tracings which result from administration of the followingcompositions formed from 20 mg adenosine combined with varying amountsof a catecholamine: (c)1: 1 part epinephrine mixed with 500 partsadenosine; (c)2: 1 part epinephrine mixed with 1,000 parts adenosine;(c)3: 1 part epinephrine mixed with 2,000 parts adenosine; (c)4: 1 partepinephrine mixed with 4,000 parts adenosine. FIG. 1(d) illustrates fourtracings which result from administration of the following compositionsformed from 20 mg adenosine combined with varying amounts of acatecholamine: (d)1: 1 part phenylephrine mixed with 25 parts adenosine;(d)2: 1 part phenylephrine mixed with 50 parts adenosine; (d)3: 1 partphenylephrine mixed with 100 parts adenosine; (d)4: 1 part phenylephrinemixed with 200 parts adenosine. Parts are given as parts by weight.

The tracings in FIG. 2(a) illustrate the effects on blood pressure fromadministration of the following: (a)1: 10 mg/kg adenosine; (a)2: amixture of 10 mg/kg adenosine with 0.01 mg/kg norepinephrine (ratio of1000/1 adenosine to norepinephrine); (a)3: 0.01 mg/kg norepinephrine.FIG. 2(b) is a blood pressure tracing which results from administrationof a mixture of 100 mg/kg adenosine with 0.1 mg/kg norepinephrine (ratioof 1000/1 adenosine to norepinephrine).

Once the adequate concentration ratio was determined for each animal, alarge dose of the AC mixture solution was injected to test the bloodpressure responses during the administration (FIG. 2(b)). A series ofnine experiments were carried out in the rabbit model to estimate anddetermine the AC concentration ratio that showed minimal blood pressurechanges, and to determine the effectiveness of the AC compositionshaving varying dosages and ratios of adenosine compounds tocatecholamines. The cardio-respiratory vital signs of the rabbits werecontinuously monitored during and after administration of the ACmixture. Table 1 summarizes the effective concentration ratio ofadenosine and 4 different catecholamines in mixtures administered to 9animals which demonstrated minimum variations in blood pressure.

                  TABLE 1                                                         ______________________________________                                        Determination of Concentration Ratios of Adenosine (A)                        and Catecholamines (C) Which Demonstrated Minimum Blood                       Pressure Fluctuations. (Parts by Weight Adenosine to 1                        Part by Weight of Designated Catecholamine.)                                  Catecholamine/Adenasine                                                       Rabbit #                                                                              Norepinephrine                                                                           Epinephrine                                                                             Dopamine                                                                             Phenylephrine                             ______________________________________                                        1       1/1000     1/2000    1/5.0  1/200                                     2       2000       4000      5.0    200                                       3       1000       2000      5.0    100                                       4        500       1000      2.5     50                                       5       1000       2000      5.0    100                                       6        500       1000      2.5     50                                       7        500       1000      2.5     50                                       8       1000       2000      5.0    100                                       9       1000       2000      5.0    100                                       Mean ± SD                                                                          944 ± 464                                                                             1889 ± 928                                                                           4.2 ± 1.3                                                                         106 ± 59                               C/A Ratio                                                                             1/944      1/1889    1/4.2  1/106                                     ______________________________________                                    

Through these in vivo tests, the concentration ratios which causeminimum fluctuations in blood pressure can be determined for eachcombination of purine compound and counteracting agent. FIG. 2(a) showsthe blood pressure changes when adenosine (ADO), norepinephrine (NE) andtheir combination (AC) is injected. The recordings demonstrate thatadministration of adenosine only (10 mg/kg, Tracing 1) causes profoundhypotension. Likewise norepinephrine only (0.01 mg/kg, Tracing 3) causesexcessive hypertension. However, the fluctuations (up and down) in theblood pressure are minimal after injection of the same dosages ofadenosine (10 mg/kg) and norepinephrine (0.01 mg/kg) combined in-vitroprior to administration (ratio of 1000/1 adenosine to norepinephrine).The blood pressure recording in FIG. 2b illustrates the stability of amammal's blood pressure during administration of a large dose of AC(ADO: 100 mg/kg, and NE: 0.1 mg/kg, ratio of 1000/1 adenosine tonorepinephrine) manually administered over a duration of about 10minutes.

Table 2 summarizes the hemodynamic, respiratory and metabolic dataobtained before and after intravenous injection of an ACB(Adenosine-Catecholamine-Benzodiazepine) combination in spontaneouslybreathing rabbits (the benzodiazepine added in this example ismidazolam, which acts as a CNS depressant as well as an adenosine uptakeinhibitor).

                  TABLE 2                                                         ______________________________________                                        Cardiovascular, Respiratory and Metabolic Data Before                         and After Intravenaus Injection of                                            Large Doses of ACB in Spontaneously Breathing Rabbits                                             Post-                                                                Pre-injection                                                                          injection Δ P                                                  (5 min before)                                                                         (5 min after)                                                                           Change  Value                                   ______________________________________                                        Blood Pressure (mmHg)                                                         Systolic (SBP)                                                                             116 ± 7 113 ± 7                                                                              -3    NS                                    Diastolic (DBP)                                                                            85 ± 6  76 ± 11                                                                              -9    NS                                    Mean (MAP)   95 ± 6  90 ± 9 -5    NS                                    Heart Rate (HR)                                                                            240 ± 31                                                                              239 ± 37                                                                             -1    NS                                    (beats/min)                                                                   Arterial Blood Gases                                                          pH           7.40 ± 0.09                                                                           7.33 ± 0.08                                                                          -0.07 0.015                                 PCO.sub.2 (mmHg)                                                                           28 ± 4  32 ± 10                                                                              +4    NS                                    PO.sub.2 (mmHg)                                                                            583 ± 21                                                                              574 ± 19                                                                             -9    NS                                    BE (mEQ/L)   -5.4 ± 5.1                                                                            -8.0 ± 4.2                                                                           -2.6  0.005                                 Respiratory Rate (RR)                                                                      71 ± 22 71 ± 30                                                                              0     NS                                    (breath/min)                                                                  Body Temperature (BT)                                                                      38.5 ± 0.05                                                                           38.2 ± 0.6                                                                           -0.3  NS                                    ° C.                                                                   ______________________________________                                         (ACB (Adenosine/Catecholamine/Benzodiazepine) in 0.9% saline); Adenosine      (117 ± 41 mg/kg); Norepinephrine (0.106 ± 0.05 mg/kg); Midazolam        (1.05 ± 0.43 mg/kg); N = 9, Mean ± SD.                             

As can be appreciated from the data in Table 2, the administration ofhuge doses of adenosine: 117±41 mg/kg, norepinephrine: 0.106±0.051mg/kg, and midazolam: 1.05±0.43 mg/kg caused minimal changes in all ofthe hemodynamic, respiratory and metabolic parameters of the subjects.These data and the recordings in FIG. 2(a) and 2(b) clearly demonstratethat large doses of adenosine and norepinephrine, combined in vitro inaccordance with the invention, can be safely administered in order toinduce a desired effect (e.g., analgesia, sedation, etc . . . ) withoutcausing deleterious cardiovascular, respiratory, or metabolicconditions.

The model system represented in the above example is designed to testthe BP responses of the healthy, normotensive animal. However, thepresent method or principle is expected to be applicable to humans aswell, particularly in view of the known effects of administering dosagesof purine compounds and catecholamine compounds to humans.

In addition, administration of large dosages of adenosine or ATPcombined with the appropriate ratio of a catecholamine can be injectedto more quickly induce a desired effect, e.g., anesthesia, than byslowly infusing low dosages of adenosine or ATP alone. It has also beensurprisingly discovered that, while the vasodilating effects ofanesthetically effective amounts of purine compounds, such as adenosineor ATP, last about as long as the purine compounds remain at theeffective concentrations in the blood plasma, certain effects, such asanalgesia, last for much longer time periods. Thus, a patientadministered a purine composition in accordance with the presentinvention to induce anesthesia may not require any, or as much, painreducing drugs following surgery. Further, administration of purinecompositions formed in accordance with the present invention reduces therelease of endogenous catecholamines in response to trauma (such as thatinduced in surgery). Thus, administration of a purine composition of thepresent invention is believed to reduce the need for an anesthesiologistto administer drugs to counteract endogenous catecholamine inducedeffects during surgery.

EXAMPLE 2 Central Nervous System (CNS) Inhibition by Administration ofACB (Adenosine-Catecholamine-Benzodiazepine)

The broad depressant effects on the CNS of exogenously administeredadenosine, adenosine analogs and adenine nucleotides are welldocumented; those related to antinociception, reduction in sensing pain,have been reviewed extensively. It is believed that a major problem ofthe hypotensive effects of adenosine may complicate the systemic routesof administration to a point where therapeutic considerations arelimited. Therefore, the present study was undertaken to find out whetherintravenous administration of ACB could attain CNS inhibitory actions,such as sedative and analgesic effects, without causing severehypotension.

Materials and Methods:

Unmedicated, healthy New Zealand white rabbits were studied. The animalswere prepared as in Example 1. The sedative and antinociceptive effectswere tested following the methodology described in Example 1 of U.S.Pat. No. 5,677,290, which is useful for testing and screening theanalgesic and anesthetic effects of adenosine compounds.

A pair of stimulating needle electrodes were placed at the base of theshaved tail of each rabbit. After the animals were placed in a sling andhad complete recovery from anesthesia, electrical current (noxiousstimuli) was delivered through a nerve stimulator (Grass S48Stimulator); in addition, conventional tail clamping (a standard testfor anesthetic effects) was done. The control values were measured andrecorded. No other drug was used, and the animals were allowed to breath100% O₂ spontaneously without mechanical ventilatory assistance. Bloodpressure changes were continuously monitored and recorded.Neurobehavioral responses, including degree of sedation, arousalresponses (eye opening and head lifting), and antinociceptive responses(purposeful escape movement) were carefully observed and recordedthroughout the experiment.

A large dose of ACB (adenosine: 100 mg/kg, norepinephrine: 0.1 mg/kg,midazolam: 1 mg/kg) was slowly injected into a peripheral ear vein overa duration of about 10 minutes. After 20 minutes, three types ofelectrical stimulation, 2 Hz, 5 Hz, and 50 Hz, were delivered to therabbits. By changing the voltage intensity, two behavioral responseswere recorded for each test: a) head lift (HL), an arousal responseshown by opening the eyes and lifting the head (hypnotic/sedativeindex); and b) purposeful escape movement, as in trying to run, orescape movement (EM) away from the noxious stimulus (analgesic index).Noxious stimuli were delivered every 30 minutes, and the sedative andnociceptive thresholds were recorded. Also, the blood pressure (BP), theheart rate (HR), EKG, respiratory rate, blood gases (PaCO₂ and PaO₂),and blood pH and base excess (BE) were recorded.

Results and Conclusions.

The administration of ACB caused minimal blood pressure changes similarto the BP changes illustrated in FIG. 2(b) where the same dosage of 100mg/kg adenosine and 0.1 mg/kg norepinephrine was administered. Inaddition, the animals were all well sedated, which is supported by theelevation of the sedative (HL) responses to electrical stimulation. Theantinociceptive (EM) as well as the sedative (HL) thresholds wereconsistently elevated in all three types of electrical stimulation afteradministration of ACB. The animals also did not respond to tailclamping, indicating a potent CNS mediated depressant effect.Furthermore, such sedative and analgesic activity was sustained for atleast three hours after administration, as is illustrated in FIG. 3. Atall three ETS levels (2 Hz, 5 Hz & 50 Hz), the thresholds for bothescape movement and head lift were consistently elevated followingadministration of the ACB composition.

FIG. 4(a) is a blood pressure tracing (mm Hg) over time, that shows,moving left to right, the effects of administering bolus injections of0.1 mg/kg adenosine triphosphate (ATP), 1.0 mg/kg ATP, 10 mg/kg ATP, and10 μg/kg norepinephrine, (NE). FIG. 4(b) shows the blood pressure, BP,recording obtained during continuous infusion of a very large dose of AC(ATP:200 mg/kg, and norepinephrine:0.67 mg/kg) which was initiated 10minutes after administration of 2 mg/kg diazepam (a sedative). Themixture of ATP and catecholamine is also referred to as AC. A totaldosage of 200 mg/kg ATP and 0.67 mg/kg norepinephrine is supplied via acontinuous infusion of AC (ratio of ATP to NE of 300/1). The continuousinfusion of AC was initiated at ATP 100 μg/kg/min, then increased to3200 μg/kg/min where it was maintained for about 30 minutes, andthereafter the dosage was decreased gradually toward the end of theinfusion. This further shows that large doses of ATP and norepinephrinecombined in vitro in accordance with the invention can be administeredwhile maintaining stable blood pressure at variable rates of infusionfor a long time.

The above BP recording illustrated in FIG. 4(a) demonstrates the BPswings during administration of ATP and norepinephrine alone. Noticethat 0.1, 1.0, and 10 mg/kg of ATP caused hypotensive effects in a dosedependent manner. Likewise, a small dose of norepinephrine (0.01 mg/kg)caused excessive elevation of the BP. However, FIG. 4(b) illustrates thereduction in the blood pressure pendulum effect which would otherwiseoccur from administration of ATP or NE separately, and the BP changesare minimal when the AC combination is administered, despite the hugedosage of ATP and norepinephrine.

FIG. 5 illustrates that following the administration of diazepam (2mg/kg) and AC (ATP: 200 mg/kg combined with NE: 0.67 mg/kg), analgesiceffects can be sustained for at least 5 hours. In FIG. 5, the verticalaxis represents sedative and analgesic thresholds in response toelectrical tail stimulation (ETS) in voltage (V). The horizontal axisrepresents time in minutes and the time at which drugs wereadministered. AC was administered as a continuous infusion over 60minutes. FIG. 5 illustrates that sedative and analgesic effects aresustained for over five hours after administration of AC, despiteadministration of flumazenil, a diazepam antagonist. Aminophylline didnot completely antagonize the escape movement (EM) antinociceptiveresponse but lowered the head lift (HL) arousal response. Thecardiovascular, respiratory and metabolic changes are shown in Table 3.

                                      TABLE 3                                     __________________________________________________________________________    Cardiovascular, Respiratory and Metabolic Data Before,                        During and After AC Adininistration                                                       Diazepam                                                                      10 min                                                                             During AC                                                                           Post AC Administration                                         Control                                                                           After                                                                              Infusion                                                                            30 min                                                                            1 hr                                                                              2 hrs                                                                             3 hrs                                                                             4 hrs                                                                             5 hrs                              __________________________________________________________________________    BP (mmHg)                                                                             89  92   77    106 106 105 102 99  107                                HR (beats/min)                                                                        214 236  226   198 211 206 200 206 234                                PaCO.sub.2 (mmHg)                                                                     34.6                                                                              31.0 32.8  21.2                                                                              29.4                                                                              31.2                                                                              32.1                                                                              34.7                                                                              32.4                               PaO.sub.2 (mmHg)                                                                      548 490  551   517 502 549 508 498 435                                BE      -6.7                                                                              -6.4 -1.1  -5.8                                                                              -1.0                                                                              -0.2                                                                              0.4 1.2 2.0                                RR (breath/min)                                                                       40  50   180   140 160 130 90  90  100                                BT (° C.)                                                                      36.9                                                                              36.9 36.6  36.4                                                                              37.4                                                                              37.8                                                                              37.8                                                                              37.7                                                                              38.0                               __________________________________________________________________________     AC (ATP: 200 mg/kg, Norepinephrine: 0.67 mg/kg); Diazepam: 2 mg/kg; BP:       Blood Pressure; HR: Heart Rate; RR: Respiratory Rate; BT: Body                Temperature.                                                             

The above studies demonstrate that AC, or AC combined with a sedative,can be effectively administered without the side effects of physicaldiscomfort and/or hypotension while achieving CNS inhibitory effects ofsedation and analgesia, and without respiratory depression or metabolicdeterioration.

EXAMPLE 3 Protection from High-Dose Opioid-Induced Cardio-Respiratoryand Metabolic Disturbances with Pretreatment by Administration of AC toSpontaneously Breathing Rabbits.

Administration of high doses of opioids has been the most frequentlyused anesthetic technique for open-heart surgery. However, the use ofhigh doses of synthetic opioids (e.g., fentanyl, sufentanil, alfentanil)has been reported to cause central seizure activity, and to increaseboth sympathetic and parasympathetic (vagal) activities with excessivelyelevated plasma catecholamine levels. In addition, opioids may causeprofound respiratory depression and serious signs of cardiopulmonarydysfunctions, including ischemic EKG abnormalities, hemorrhagicpulmonary congestion and left ventricular failure of the heart. Incontrast, exogenously administered adenosine has been reported tostimulate ventilation and has been found to have potent analgesiceffects. We hypothesized that, if sufficiently large dosages of AC(e.g., adenosine-norepinephrine) could be administered safely, thiscould protect mammals from the above mentioned deleterious effects ofhigh opioid dosages. Therefore, the present study investigated whetherintravenous administration of AC could protect against thecardio-pulmonary and metabolic disturbances caused by the administrationof high doses of fentanyl.

Materials and Methods:

The experimental preparation was done as in Example 1. Tracheotomizedand cannulated rabbits were each placed in a suspended sling. Theanimals were divided into 2 groups. Each group consisted of 4 animals:The rabbits were pretreated with (a) saline or (b) AC (combination ofATP:100 mg/kg and NE: 0.2 mg/kg). A high dose of fentanyl: 100 μg/kg(Janssen Pharmaceutica, New Jersey) was administered twice. The firstinjection was 10 minutes after the pretreatment with saline or AC, andthe second dose was administered after 40 minutes. Cardiovascular andblood gas data were recorded right after the pretreatment drug wasadministered, and then at 5, 10, 20 and 30 minutes followingadministration of fentanyl. Also, the neuro-behavioral and thenociceptive thresholds were assessed as in Example 2 by tail clampingand electrical tail stimulation.

Results and Conclusion:

Data are summarized in FIGS. 6(a)-(h). Fent (fentanyl: 100 μg/kg) wasfirst injected 10 minutes after pretreatment with either pretreatment aor b, and a second injection of Fent was given at 40 minutes. Cont1 andCont2 represent control data before injection of drugs. FIG. 6(a)provides MAP: mean arterial pressure; 6(b) provides HR: heart rate; 6(c)provides PaCO₂ : arterial carbondioxide tension; 6(d) provides PaO₂ :arterial oxygen tension. Notice that administration of fentanyl producedsevere respiratory depression which resulted in a progressive increasein PaCO₂ and a decrease in PaO₂, as can be seen in 6(c) and (d). Whenhypercapnia became severe after the second administration of fentanyl,the AC pretreated group suddenly increased respiratory rate as seen in6(e) resulting in a decrease of PaCO₂ as seen in 6(c) and an increase inPaO₂ as seen in 6(d), while the metabolic parameters of pH as seen in6(g) and BE: base excess as seen in 6(h) were ameliorated.

As can be appreciated from FIGS. 6(a)-(b), the fluctuations in the bloodpressure and heart rate due to the fentanyl injections are attenuated inthe animals administered the AC composition compared to thoseadministered saline. The incidence of seizure activity and the degree ofskeletal muscle rigidity were less in the AC group than in the salinegroup (see FIGS. 6(i)-(j)). The threshold responses to noxiousstimulation in the form of electrical stimulation and tail clamping werealso higher in the AC group. These results demonstrate the beneficialeffects rendered by the pretreatment with the AC composition byprotecting the patients from the cardio-respiratory and metabolicdisturbances caused by administering a high dosage of an opioid (e.g.,fentanyl). In addition, AC rendered neuroprotection from seizureactivities.

EXAMPLE 4 Cardiopulmonary Protective Effects of the AC(Adenosine/Catecholamine) Composition

The protective and homeostatic actions of adenosine are well accepted.Extensive studies on the involvement of endogenous and exogenousadenosine in myocardial ischemia protection have been reported. Theprotective effects mediated by activation of adenosine receptors can berendered by administration of adenosine. However, administeringefficacious amounts of adenosine to attain the beneficial effects hasbeen hampered by the insurmountable obstacle of the side effects ofadenosine and has hindered a practical therapy based on theadministration of adenosine. We hypothesized that administering theinvented AC composition would allow administration of effective dosagesof adenosine to attain the desirable beneficial effects in the heart andthe lungs while attenuating the undesirable side effects ofadministering adenosine or catecholamine alone.

The pathogenesis of the catecholamine-induced myocardial necrosis hasbeen the subject of many research papers. The cardiotoxicity effects ofexcessive catecholamines are well known. Sustained infusions orexcessive doses of catecholamines administered to experimental animalsproduce myocardial dysfunction, ischemic lesions, necrosis and inaddition, hemorrhagic pulmonary congestion, edema and ultimately death.This experimental model has had wide acceptance to prove the protectiveeffects of various drugs, and has clinical relevance in syndromesincluding myocardial ischemia, infarction and pulmonary edema. Opioidsare believed to attenuate the cardiovascular responses to surgicalstress. It is thought that the cardiopulmonary detrimental effects ofcatecholamines can be suppressed by opioids. Thus, the use of high dosesof opioids including sufentanil is a common practice in cardiopulmonarybypass surgery. The study was undertaken to determine whether thepresent ACB composition could prevent cardiac damage, pulmonary edemaand death induced by challenging rabbits with high doses ofcatecholamines. The effects were compared to those of sufentanil.

Materials and Methods:

Drugs:

For Protocol A: ACB (Adenosine-Catecholamine-Benzodiazepine)Composition: A=adenosine: 100 mg/kg, C=norepinephrine: 0.1 mg/kg,B=midazolam: 1 mg/kg. sufentanil: 15 μg/kg (Janssen Pharmaceutica,Titusville, N.J).

For Protocol B: Epinephrine ratio to Adenosine or ATP was 1/160, 8-PT(8-phenyltheophylline) 25 mg/kg from Research BiochemicalsInternational, Natick, Mass.

Unmedicated, healthy adult New Zealand white rabbits of either sex,weighing 2.5-2.7 kg were studied and the preparation was done as inExample 1. After the prepared and tracheotomized rabbits were placed inthe sling with all the monitoring in place, the hemodynamic blood gasand metabolic parameters were measured for the control values. Therewere two experimental protocols. The protective effects of the presentcomposition, AC, were compared with those of sufentanil and saline(control) in Protocol A, and with those of saline (control) and 8-PT inProtocol B. The adverse functional effects of catecholamines,norepinephrine (NE) and epinephrine (Epi) were studied in the in vivoanimal experimental model. This was done by a continuous infusion intothe marginal ear vein of high doses of the above catecholamines whichprovided cardiotoxic stimulation. The infusion of the drugs was slowlydone in spontaneously breathing rabbits except for the sufentanil groupin which ventilation was mechanically controlled. Using a TravenolFlo-Gard 8000 volumetric infusion pump, the catecholamines, NE or Epiwere continuously infused into the marginal ear vein for two and threehours respectively.

Protocol A:

The study was divided in two groups, both groups received high doses oftwo hours continuous infusion of norepinephrine (NE) as a cardiotoxicstimulant. In Group I, the rabbits were subjected to 20 μg/kg/min (NE),and in Group II, the rabbits were subjected to 40 μg/kg/min (NE). Ineach group, the animals were randomly assigned to a subgroup (n=6 foreach subgroup): a) saline, b) sufentanil, c) ACB composition. All of thestudied drugs (saline, sufentanil, ACB composition) were given as apre-treatment drug prior to starting the NE infusion. Midazolam was usedto sedate the animals in order to avoid excitation due to discomfortduring administration of the drugs.

Protocol B:

In this study, the animals were subjected to 10 μg/kg/min of Epi as acardiotoxic stimulant. In the AC and ATPC groups, epinephrine andadenosine or ATP were mixed at a ratio of 1/160. The mixed solutionswere continuously infused for 3 hours. At the beginning of the infusion,the doses were titrated to the cardiovascular responses, and graduallyincreased. The animals were randomly assigned in subgroups of a) saline(n=6), b) 8-PT (n=6), AC (adenosine/epinephrine, n=8), ATPC(ATP/epinephrine: n=2). In order to antagonize the endogenous adenosine,8-PT (8-phenyltheophylline), an adenosine receptor antagonist was used.

Results and Conclusion:

The results for Protocol A are summarized in FIGS. 7(a)-(d). FIGS. 7(a)and 7(b) illustrate the mortality rate, and FIGS. 7(c) and 7(d)illustrate the rate that developed pulmonary edema (PE) when rabbits inGroup I, FIGS. 7(a) and 7(c), were subjected to 20 μg/kg/min NE, andrabbits in Group II, FIGS. 7(b) and 7(d), were subjected to 40 μg/kg/minNE. The figures show that in Group II, FIG. 7(b) and (d), where higherdoses of NE (40 μg/kg/min) were infused, 6/6, 100% of the animals diedin the sufentanil group, 5/6 or 83% in the saline, and 2/7 or 28% in theACB group died within 3 hours. In the Group I, FIG. 7(a) where theanimals were challenged by 20 μg/kg/min of NE, all the ACB pretreatedanimals survived (100%) for two hours, and one died after 150 minutes.Compared to the saline group where the mortality rate was 3/6 (50%) orthe sufentanil group where the mortality rate was 4/6 (67%) within 180minutes. The number of animals that developed pulmonary congestion andedema are also much higher in the saline or sufentanil groups than inthe group administered with the ACB composition (FIGS. 7(c)-(d)). Theblood gas data was progressively deteriorated in both the saline andsufentanil groups. However, no significant blood gas and metabolicchanges were shown in the survived animals of the ACB groups.

The results are summarized in FIGS. 8(a)-(b) for Protocol B in whichanimals were challenged by high doses of Epi. FIG. 8(a) shows themortality rate, and FIG. 8(b) shows the rate of rabbits that developedpulmonary edema (PE). As can be seen from FIGS. 8(a) and (b), almost 70%of the animals developed pulmonary edema and died within 30-60 minutesin the 8-PT and saline groups. In contrast, administration of thepresent composition, AC or ATPC could effectively prevent thedevelopment of pulmonary edema and death in most of the studied animals.The myocardial and pulmonary ischemic insult appeared to be involved inthe catecholamine-induced damage and death which was apparent in the ECGand blood gas changes. The above results clearly demonstrate thatadministration of the present composition, AC, ACB or ATPC resulted in asignificant reduction of pulmonary congestion and edema as well ascardiovascular damage and death in both protocols. The presentcomposition effectively protected the heart and the lungs during acutelyinduced stressful and cardiotoxic stimulation challenged by large dosesof catecholamine infusions.

EXAMPLE 5 Metabolic Homeostasis Maintaining and Protection of Ischemiaby Administration of the AC Composition

Homeostasis, the biologic responses necessary to maintain a steady statein the internal environment, is necessary for survival. Maintenance ofthe body's internal milieu is the major function of buffering systems,while oxygen transport and the successful preservation of aerobicmetabolism are key components in maintaining cellular integrity. Asnormal aerobic metabolism is compromised or as the ratio of bufferingelements is altered, disturbances in acid-base homeostasis occur.Lactate accumulation in extracellular fluid is due to an imbalancebetween oxygen supply and metabolic demand. Lactic acidosis isassociated with tissue hypoxia and impaired oxidative metabolism.Tissues that normally can use oxygen to produce ATP from glucosewill-resort to the less energy-efficient glycolytic pathway if oxygen isunavailable. Under anaerobic conditions, lactate production willtherefore increase, and since lactate is readily diffusible across cellmembranes, the concentration of lactate in the blood will increase. Thisis the basis of blood lactate as a marker of tissue ischemia/hypoxia. Apractical indicator is the hydrogen ion level as expressed in baseexcess (BE) determined by the arterial blood sample.

Lactic acidosis is a metabolic derangement associated with a variety ofpathological states including excessive levels of stress caused byintense stimulation like major body injury, surgical or accidental. Thedegree of increase in the lactate level seems to correlate directly withthe severity of levels of stress. Moreover, increases in lactate mayreflect increased activity of the sympathetic nervous system andincrease catecholamine release due to stress. Thus, responses to excesslactate are believed directly related to activation of the sympatheticnervous system after a variety of stresses, including anxiety,hypotension and major injuries. The degree of sympathetic nervous systemactivity and consequent release of endogenous catecholamines candirectly influence the responses observed, since both epinephrine andnorepinephrine result in increased blood levels of lactate and increasedrates of anaerobic glycolysis in many tissues/organs. Theseconsiderations are particularly relevant in considering the responses toischemia, hypoxia, anesthesia, surgery, hemorrhage, trauma and shockwhich are so dependent upon sympathetic nervous system activation andrelease of catecholamines.

Severe stress caused by stimuli such as surgical intervention inducesacute disorders in endocrine, hormonal and cardiovascular systems. Forexample, traction and manipulation of the viscera during abdominalsurgery in addition to the general biologic response to stress are knownto be associated with marked increase in circulating catecholamines,mesenteric vasoconstriction and a decrease in gastrointestinal bloodflow which may cause ischemia-reperfusion injury in various splanchnicorgan systems, resulting in compromised organ function and increase inlactate levels (lactic acidosis). We designed an experimental model thatcan mimic the above conditions of intense sympathetic activation,release of catecholamines, severe vasoconstriction that may be transientbut likely to cause ischemia-reperfusion injury in the splanchnicorgan/tissues. This could be induced by delivering stressfulintra-abdominal electrical stimulation. The stress response to noxiousstimulation further yields a subsequent increase in oxygen demand whichwould worsen the imbalance of oxygen supply/demand. The measurement ofblood gas/acid-base metabolic status as a useful tool in the assessmentof critically ill patients and patients undergoing severe stress liketrauma or surgery is well recognized. For example, elevation of bloodlactate level often alerts the clinician for the need to rapidlyinstitute appropriate monitoring and potentially lifesaving therapy.

It is thought that adenosine acting via adenosine receptor activationcan play a homeostatic role, that adenosine functions as a retaliatorymetabolite in response to tissue trauma, hypoxia and ischemia. Undersuch conditions, tissue levels of adenosine are markedly increasedbecause of ATP breakdown. It is also believed that the anti-adrenergiceffects of adenosine can be beneficial to inhibit detrimentalsympathetic activation and that administration of adenosine could bebeneficial. Therefore, we sought to determine whether the invented AC(adenosine/norepinephrine) composition could attenuate or prevent themetabolic disturbances caused by stressful noxious stimuli in theintestine, and inhibit the sympathetic responses which may lead tomesenteric vasoconstriction with subsequent ischemia-reperfusion injury.

Methods and Materials

Drugs: AC (adenosine/norepinephrine ratio: 800/1 dissolved in saline) ACinfusion, adenosine: 400 μg/kg/min; 8-phenyltheophylline (8-PT): 25mg/kg; glibenclamide: 15 mg/kg.

The preparation of the animals was done as in Example 1. The preparedand tracheotomized rabbits were placed in a sling which allowed easyobservation of the behavioral responses without restraining the animals.The cardiovascular, respiratory and metabolic monitoring was instituted.The baseline control values were then taken. EKG and hemodynamic changeswere continuously monitored throughout the experiments. In addition,intermittent blood gases and the metabolic changes were measured beforeand after noxious stimulations. The electrical stimulation was appliedat 20 minutes intervals (3 series). As is illustrated in FIG. 9, threegroups of rabbits were studied: a) AC group (n=5), b) saline group(n=7); c) 8-PT+glibenclamide group (n=5). In group (c), 8-PT andglibenclamide were used in order to block endogenous release ofadenosine and its effects on ATP sensitive K ion channels. 8-PT is anadenosine receptor antagonist, and glibenclamide is an ATP-dependent K+channel blocker. In group (c) 8-PT was administered first, and after 15minutes, libenclamide was administered. In all the 3 groups (a,b,c),anesthesia was maintained with 1.4% isoflurane throughout all theexperiments. In groups (a) and (b), noxious electrical visceralstimulation (EVS) was applied after 1 hour continuous infusion of AC,(adenosine, 400 μg/kg/min) or saline. The AC infusion was continuedthroughout the tested stimulation (EVS #1-#3). Electrical current wasdelivered through a nerve stimulator via electrodes that were introducedinto the rectum about 10-13 cm. Electric current at predeterminedintensities of 50 Hz, 80 volts were applied for 40 seconds. Behavioralresponses such as bodily movement and the hemodynamic responses werecarefully monitored and recorded. The blood gas variables were measuredright after stimulation and every 5 minutes afterwards.

Results and Conclusion:

Despite the fact that the animals were anesthetized with 1.4%isoflurane, when high intensity electric current was delivered, therewas marked increase in blood pressure, heart rate, and the animalshyperventilated. The animals also moved violently, particularly in thesaline and 8-PT+glibenclamide groups. In contrast, these behavioral andthe hemodynamic responses were quite inhibited in the AC group. As FIG.9 shows, the metabolic acidosis (decrease in BE) was progressivelydeteriorated and exaggerated particularly in the 8-PT+glibenclamidegroup (c), where the endogenous adenosine release and the KATP channelactivities were blocked. The metabolic conditions of these animalsprogressively worsened as time passed, after each stimulation (See FIG.9), and ultimately all the animals died in group (c). In comparison, themetabolic disturbances (decrease in BE) in the AC group were minimal,and did not show any pathological condition. Twenty minutes after thelast stimulation (EVS #3), the AC group animals completely recovered tonormal ranges.

The results indicate that intravenous administration of the present ACcomposition effectively inhibited excessive sympathetic activities andmesenteric vasoconstriction caused by intense noxious stimulation, andcould greatly attenuate metabolic derangements in the animals exposed tosevere stressful conditions. Therefore, it can be concluded thatprotection against trauma and subsequent ischemia-reperfusion injury inthe splanchnic organs/tissues occurred.

Although the above example was indirectly assessing splanchnicorgans/tissues ischemia-reperfusion injury possibly caused by thetraumatic stimulation and excessive visceral vasoconstriction, thepresent method is expected to be applicable to any tissue/organ that hassuffered from ischemic/hypoxic damage. In addition, the AC compositionis expected to be useful in critically ill patients where lacticacidosis is common and is usually caused by inadequate tissue perfusionthat does not meet metabolic demand. The present composition may bebeneficial to aid metabolic adjustments following accidental trauma. Thepresent method may also be beneficial to accelerate general recovery inpatients in the ICU (Intensive Care Unit). The present method is alsoexpected to be applicable to other situations which include but are notlimited to: stroke, in vivo organ preservation and transplant, traumaand shock which results from poor circulatory conditions, and a varietyof pathological states resulting from metabolic disturbances.

EXAMPLE 6 Intravenous Administration of a Combination of AdenosineAnalog (R-PIA)-Catecholamine

Unmedicated, healthy New Zealand white rabbits were prepared as inExample 1. Anesthesia was maintained with isoflurane 1.4% throughout allthe experiments. A mixture of 5.0 mg. of an adenosine analog compound,R(-)N-(2-phenylisopropyl) adenosine (R-PIA) and 0.1 mg of norepinephrine(NE) was administered by intravenous infusion over a period of about 10minutes. The initial blood pressure of about 100 mmHg gradually droppedduring the infusion. When the initial infusion was stopped, bloodpressure began to fall, as the norepinephrine was metabolized morequickly than the R-PIA, and resulting in increased hypotension. Tocounter this hypotensive condition, a separate continuous infusion of 4μg/kg/min of norepinephrine (NE) was administered for a period of about5 minutes to support blood pressure at about 75-80 mmHg, followed byadministration of a continuous infusion of 2 μg/kg/min of norepinephrineto maintain and stabilize blood pressure near normotensive levels. Theresults of the initial infusion of the mixture of R-PIA andnorepinephrine, followed by a staged, separate continuous infusion ofnorepinephrine are shown in the blood pressure tracing of FIG. 10.

EXAMPLE 7 Intravenous Administration of a Combination of AdenosineAnalog (R-PIA)-Catecholamine

Unmedicated, healthy New Zealand white rabbits were prepared as inExample 1. Anesthesia was maintained with isoflurane 1.4% throughout allthe experiments. A mixture of 5.0 mg. of an adenosine analog compound,R(-)N⁶ -(2-phenylisopropyl)adenosine (R-PIA) and 0.1 mg ofnorepinephrine was initially administered by intravenous infusion over aperiod of about 13 minutes, as in Example 6. However, administration ofa separate continuous infusion of 4 μg/kg/min of norepinephrine (NE) wasbegun about halfway through the initial infusion of the mixture, and wascontinued for a period of about 10 minutes to stabilize blood pressure.This was followed by reduction of the continuous infusion ofnorepinephrine to 2 μg/kg/min to maintain and stabilize blood pressurenear normotensive levels. The results of the initial infusion of themixture of R-PIA and norepinephrine, accompanied by a staged, separatecontinuous infusion of norepinephrine, are shown in the blood pressuretracing of FIG. 11.

EXAMPLE 8 Intravenous Administration of a Combination of AdenosineAnalog (NECA)-Catecholamine

Unmedicated, healthy New Zealand white rabbits were prepared as inExample 1. Anesthesia was maintained with isoflurane 1.4% throughout allthe experiments. A mixture of 1.25 mg. of an adenosine analog compound,5'-N-ethylcarboxamidoadenosine (NECA) and 0.2 mg of norepinephrine (NE)was initially administered by intravenous infusion over a period ofabout 13 minutes. Administration of a separate continuous infusion of 60μg/kg/min of norepinephrine (NE) was begun about 1-2 minutes followingthe commencement of infusion of the mixture, and was continued tomaintain and stabilize blood pressure at normotensive levels. Theresults of the initial infusion of the mixture of NECA andnorepinephrine, accompanied by a separate continuous infusion ofnorepinephrine, are shown in the blood pressure tracing of FIG. 12.

While the principles and exemplary embodiments of the present inventionhave been discussed herein, many variations and modifications can bemade to the invention as disclosed without departing from the spirit andscope of the invention.

We claim:
 1. A pharmaceutical composition, comprising:a purine compoundand a catecholamine compound in a pharmaceutically acceptable carrier.2. The composition of claim 1, whereinthe ratio of active compounds isselected so that the purine compound produces said desired effect andthe catecholamine compound reduces the undesired side effects of saidpurine compound.
 3. The composition of claim 1, wherein said purinecompound is selected from the group consisting of adenosine, adenosinemonophosphate, adenosine diphosphate, adenosine triphosphate,5'-N-ethylcarboxamidoadenosine, R(-)N⁶ -(2-phenylisopropyl)adenosine,2-chloroadenosine, N⁶ -cyclopentyladenosine, and N⁶-cyclohexyladenosine.
 4. The composition of claim 1, wherein saidcatecholamine compound is selected from the group consisting ofepinephrine, norepinephrine, dopamine, dobutamine, and phenylephrine. 5.The composition of claim 3, wherein said catecholamine compound isselected from the group consisting of epinephrine, norepinephrine,dopamine, dobutamine, and phenylephrine.
 6. The composition of claim 1,wherein said purine compound is selected from the group consisting ofadenosine, adenosine monophosphate, adenosine diphosphate, adenosinetriphosphate, 5'-N-ethylcarboxamidoadenosine, R(-)N⁶-(2-phenylisopropyl)adenosine, 2-chloroadenosine, N⁶-cyclopentyladenosine, and N⁶ -cyclohexyladenosine,when saidcatecholamine compound is norepinephrine, said composition comprisesabout one part by weight norepinephrine to about 25 to about 2000 partsby weight purine compound; when said catecholamine compound isepinephrine, said composition comprises about one part by weightepinephrine to about 50 to about 4000 parts by weight purine compound;when said catecholamine compound is phenylephrine, said compositioncomprises about one part by weight phenylephrine to about 10 to about200 parts by weight purine compound; and when said catecholaminecompound is dopamine, said composition comprises about one part byweight dopamine to about two to about five parts by weight purinecompound.
 7. The composition of claim 6, wherein said purine compound isadenosine.
 8. A method for inducing in a mammal in need thereof adesired effect, comprising administering a combination of a purinecompound and a catecholamine compound whereinthe ratio of the compoundsis selected so that the purine compound produces said desired effect andthe catecholamine compound reduces the undesired side effects of saidpurine compound, and wherein said administering of said compounds is asa single composition, or wherein said administering of said compounds issimultaneous in the form of two separate compositions, in an amounteffective to induce said desired effect.
 9. The method of claim 8,wherein said purine compound is selected from the group consisting ofadenosine, adenosine monophosphate, adenosine diphosphate, adenosinetriphosphate, 5'-N-ethylcarboxamidoadenosine, R(-)N⁶-(2-phenylisopropyl)adenosine, 2-chloroadenosine, N⁶-cyclopentyladenosine, and N⁶ -cyclohexyladenosine.
 10. The method ofclaim 8, wherein said catecholamine compound is selected from the groupconsisting of epinephrine, norepinephrine, dopamine, dobutamine, andphenylephrine.
 11. The method of claim 9, wherein said catecholaminecompound is selected from the group consisting of epinephrine,norepinephrine, dopamine, dobutamine, and phenylephrine.
 12. The methodof claim 8, further comprising:combining a purine compound potentiatorwith said purine compound and said catecholamine compound prior toadministration to a mammal.
 13. The method of claim 12, wherein saidpurine compoundpotentiator is selected from the group consisting ofbenzodiazepine, dipyridamole, deoxycoformycin,erythro-9-(2-hydroxy-3-nonyl)adenine, AICA riboside, an opioid,etomidate, propofol, an adrenergic α₂ -agonist, a barbiturate, and anon-steroidal anti-inflammatory drug.
 14. The method of claim 8, furthercomprising the step of administering to said mammal an infusion of acatecholamine compound subsequent to said step of administering saidcombination.
 15. The method of claim 14, wherein said step ofadministering an infusion of said catecholamine compound comprisesadministering said catecholamine compound in a plurality of stages ofcontinuous infusion of progressively decreasing dosages of saidcatecholamine compound.